Superchargers and turbocharger are used to increase the amount of air supplied to an internal combustion engine. Both these systems increase the pressure of the air that enters the engine, thereby increasing the density of the engine intake air. Turbochargers are driven by the engine exhaust whereas superchargers are driven mechanically by the engine itself. There are a number of known advantages and disadvantages associated with both types of systems. For example, while turbochargers are recognized as being relatively more fuel efficient than superchargers, turbochargers typically have some delayed response commonly known as lag. Improved boost systems are desirable.